Medical articles can be fabricated from a number of materials. For example, some common materials utilized to fabricate medical articles include metals and alloys, ceramics, glasses, glass-ceramics, polymeric materials, composites, cements, nonwovens and fabrics. The environment of the human body is surprisingly hostile and aggressive; therefore, selection of materials to be used in the human body involves consideration of such factors as material properties, application of the medical article, duration of residence within the body, and the like. Common polymeric materials used in the human body include silicones and other plastics, while metals include stainless steels, cobalt-chromium alloys, titanium and titanium alloys, shape memory alloys and tantalum.
It can be desirable to modify the surface of a medical article to impart desirable properties to the surface (such as lubricity, biocompatibility, antimicrobial action and the like), to release bioactive agents (such as drugs) over time, to render the medical article more visible to imaging systems, and the like.
Poly(dimethyl siloxane) (PDMS) belongs to a group of polymeric organosilicon compounds that are commonly referred to as silicones. Some applications of silicones include contact lenses, medical devices, elastomers, caulking, lubricating oils, and heat-resistant tiles. Silicones have been widely used in biomedical applications because of such material properties as excellent flexibility, durability, and bioinertness. However, surface modification of silicones is often needed to achieve desirable surface properties for various applications. Modification of silicone surfaces has proven challenging due to the material's extremely low surface reactivity and surface energy. To complicate the matter further, silicones usually contain high amounts of low-molecular weight components having high mobility in the polymer bulk and high tendency to migrate to the surface. This in turn can lead to a transient modification effect for only a few hours (hydrophobic recovery).